I have written simple rest application using Spring MVC 4 (or Spring-Boot). Within the controller I have return ResponseEntity
. But in some cases I want to give success JSON and if there is validation error I want to give error JSON. Currently success and error responses are totally different, So I have created 2 classes for error and success. Within the controller I want to return ResponseEntity<Success>
, if the internal logic is okay. Otherwise I want to return ResponseEntity<Error>
. Is there any way to do it.
Success
and Error
are the 2 classes that i use to represent success and error response.
This question is related to
java
json
spring-mvc
spring-boot
Note: if you upgrade from spring boot 1 to spring boot 2 there is a ResponseStatusException
which has a Http error code and a description.
So, you can effectively use generics they way it is intended.
The only case which is a bit challenging for me, is the response type for a status 204 (ok with no body). I tend to mark those methods as ResponseEntity<?>
, because ResponseEntity<Void>
is less predictive.
You can use a map with your object or string like bellow :
@RequestMapping(value = "/path",
method = RequestMethod.GET,
produces = MediaType.APPLICATION_JSON_VALUE)
@ResponseBody
public ResponseEntity<Map<String,String>> getData(){
Map<String,String> response = new HashMap<String, String>();
boolean isValid = // some logic
if (isValid){
response.put("ok", "success saving data");
return ResponseEntity.accepted().body(response);
}
else{
response.put("error", "an error expected on processing file");
return ResponseEntity.badRequest().body(response);
}
}
For exceptional cases, I will recommend you to adopt RFC-7807 Problem Details for HTTP APIs standard in your application.
Zalando's Problems for Spring provides a good integration with Spring Boot, you can integrate it easily with your existing Spring Boot based application. Just like what JHipster did.
After adopting RFC-7087 in your application, just throw Exception in your controller method, and you will get a detailed and standard error response like:
{
"type": "https://example.com/probs/validation-error",
"title": "Request parameter is malformed.",
"status": 400
"detail": "Validation error, value of xxx should be a positive number.",
"instance": "/account/12345/msgs/abc",
}
You can return generic wildcard <?>
to return Success
and Error
on a same request mapping method
public ResponseEntity<?> method() {
boolean b = // some logic
if (b)
return new ResponseEntity<Success>(HttpStatus.OK);
else
return new ResponseEntity<Error>(HttpStatus.CONFLICT); //appropriate error code
}
@Mark Norman answer is the correct approach
Spring 2 introduced ResponseStatusException using this you can return String, different HTTP status code, DTO at the same time.
@PostMapping("/save")
public ResponseEntity<UserDto> saveUser(@RequestBody UserDto userDto) {
if(userDto.getId() != null) {
throw new ResponseStatusException(HttpStatus.NOT_ACCEPTABLE,"A new user cannot already have an ID");
}
return ResponseEntity.ok(userService.saveUser(userDto));
}
Here is a way that I would do it:
public ResponseEntity < ? extends BaseResponse > message(@PathVariable String player) { //REST Endpoint.
try {
Integer.parseInt(player);
return new ResponseEntity < ErrorResponse > (new ErrorResponse("111", "player is not found"), HttpStatus.BAD_REQUEST);
} catch (Exception e) {
}
Message msg = new Message(player, "Hello " + player);
return new ResponseEntity < Message > (msg, HttpStatus.OK);
}
@RequestMapping(value = "/getAll/{player}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity < List < ? extends BaseResponse >> messageAll(@PathVariable String player) { //REST Endpoint.
try {
Integer.parseInt(player);
List < ErrorResponse > errs = new ArrayList < ErrorResponse > ();
errs.add(new ErrorResponse("111", "player is not found"));
return new ResponseEntity < List < ? extends BaseResponse >> (errs, HttpStatus.BAD_REQUEST);
} catch (Exception e) {
}
Message msg = new Message(player, "Hello " + player);
List < Message > msgList = new ArrayList < Message > ();
msgList.add(msg);
return new ResponseEntity < List < ? extends BaseResponse >> (msgList, HttpStatus.OK);
}
I used to use a class like this. The statusCode is set when there is an error with the error message set in message. Data is stored either in the Map or in a List as and when appropriate.
/**
*
*/
package com.test.presentation.response;
import java.util.Collection;
import java.util.Map;
/**
* A simple POJO to send JSON response to ajax requests. This POJO enables us to
* send messages and error codes with the actual objects in the application.
*
*
*/
@SuppressWarnings("rawtypes")
public class GenericResponse {
/**
* An array that contains the actual objects
*/
private Collection rows;
/**
* An Map that contains the actual objects
*/
private Map mapData;
/**
* A String containing error code. Set to 1 if there is an error
*/
private int statusCode = 0;
/**
* A String containing error message.
*/
private String message;
/**
* An array that contains the actual objects
*
* @return the rows
*/
public Collection getRows() {
return rows;
}
/**
* An array that contains the actual objects
*
* @param rows
* the rows to set
*/
public void setRows(Collection rows) {
this.rows = rows;
}
/**
* An Map that contains the actual objects
*
* @return the mapData
*/
public Map getMapData() {
return mapData;
}
/**
* An Map that contains the actual objects
*
* @param mapData
* the mapData to set
*/
public void setMapData(Map mapData) {
this.mapData = mapData;
}
/**
* A String containing error code.
*
* @return the errorCode
*/
public int getStatusCode() {
return statusCode;
}
/**
* A String containing error code.
*
* @param errorCode
* the errorCode to set
*/
public void setStatusCode(int errorCode) {
this.statusCode = errorCode;
}
/**
* A String containing error message.
*
* @return the errorMessage
*/
public String getMessage() {
return message;
}
/**
* A String containing error message.
*
* @param errorMessage
* the errorMessage to set
*/
public void setMessage(String errorMessage) {
this.message = errorMessage;
}
}
Hope this helps.
Its possible to return ResponseEntity
without using generics, such as follows,
public ResponseEntity method() {
boolean isValid = // some logic
if (isValid){
return new ResponseEntity(new Success(), HttpStatus.OK);
}
else{
return new ResponseEntity(new Error(), HttpStatus.BAD_REQUEST);
}
}
You can also implement like this to return Success and Error on a same request mapping method,use Object class(Parent class of every class in java) :-
public ResponseEntity< Object> method() {
boolean b = // logic here
if (b)
return new ResponseEntity< Object>(HttpStatus.OK);
else
return new ResponseEntity< Object>(HttpStatus.CONFLICT); //appropriate error code
}
i am not sure but, I think you can use @ResponseEntity
and @ResponseBody
and send 2 different one is Success and second is error message like :
@RequestMapping(value ="/book2", produces =MediaType.APPLICATION_JSON_VALUE )
@ResponseBody
Book bookInfo2() {
Book book = new Book();
book.setBookName("Ramcharitmanas");
book.setWriter("TulasiDas");
return book;
}
@RequestMapping(value ="/book3", produces =MediaType.APPLICATION_JSON_VALUE )
public ResponseEntity<Book> bookInfo3() {
Book book = new Book();
book.setBookName("Ramayan");
book.setWriter("Valmiki");
return ResponseEntity.accepted().body(book);
}
For more detail refer to this: http://www.concretepage.com/spring-4/spring-4-mvc-jsonp-example-with-rest-responsebody-responseentity
Using custom exception class you can return different HTTP status code and dto object.
@PostMapping("/save")
public ResponseEntity<UserDto> saveUser(@RequestBody UserDto userDto) {
if(userDto.getId() != null) {
throw new UserNotFoundException("A new user cannot already have an ID");
}
return ResponseEntity.ok(userService.saveUser(userDto));
}
Exception class
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;
@ResponseStatus(value = HttpStatus.NOT_FOUND, reason = "user not found")
public class UserNotFoundException extends RuntimeException {
public UserNotFoundException(String message) {
super(message);
}
}
Source: Stackoverflow.com